1 files changed, 28 insertions, 0 deletions
diff --git a/tests/util.py b/tests/util.py
index 1355ce8a..69df87f5 100644
--- a/tests/util.py
+++ b/tests/util.py
@@ -9,6 +9,9 @@ import pytest
 from paramiko.py3compat import builtins, PY2
 from paramiko.ssh_gss import GSS_AUTH_AVAILABLE
 
+from cryptography.exceptions import UnsupportedAlgorithm, _Reasons
+from cryptography.hazmat.primitives import hashes
+from cryptography.hazmat.primitives.asymmetric import padding, rsa
 
 tests_dir = dirname(realpath(__file__))
 
@@ -144,3 +147,28 @@ def is_low_entropy():
         # I don't see a way to tell internally if the hash seed was set this
         # way, but env should be plenty sufficient, this is only for testing.
         return is_32bit and os.environ.get("PYTHONHASHSEED", None) == "0"
+
+
+def sha1_signing_unsupported():
+    """
+    This is used to skip tests in environments where SHA-1 signing is
+    not supported by the backend.
+    """
+    private_key = rsa.generate_private_key(
+        public_exponent=65537,
+        key_size=2048,
+    )
+    message = b"Some dummy text"
+    try:
+        signature = private_key.sign(
+            message,
+            padding.PSS(
+                mgf=padding.MGF1(hashes.SHA1()),
+                salt_length=padding.PSS.MAX_LENGTH
+            ),
+            hashes.SHA1()
+        )
+        return False
+    except UnsupportedAlgorithm as e:
+        return e._reason is _Reasons.UNSUPPORTED_HASH
+